<template>
    <div class="container">container</div>
</template>

<script setup>
   import { onBeforeMount, onMounted } from 'vue'
   onBeforeMount (() => {
    console.log('DOM元素渲染前', document.querySelector('.container'))
   })
   onMounted(() => {
    console.log('DOM元素渲染后', document.querySelector('.container'))
   })
</script>